Is there anything more disorienting that waking up from a
very vivid dream? Than that moment between sleeping and waking when you’re not
sure if it was a dream, and you have to pause to untangle the dream
events from real ones? I’m not someone who feels particularly in touch with my
dream life. Most of the time, I don’t remember my dreams at all, and, although once
in a while I’ll wake up knowing that I had a bad dream, or a good dream, or a
sexy dream, the dreams themselves feel cloudy and tenuous. However, once in a
blue moon, I’ll have a very vivid, very real dream that leaves me confused and
thrown. In my case, such dreams tend to be rooted in anxiety — visions of being
chased, or of not being able to go where I want to go, or of having
my teeth spontaneously fall out (Those are the WORST). I wake up feeling
anxious, and the day hasn’t even begun yet.
Why are some dreams more vivid than others? Why are some memorable, when others disappear instantly? The science of dreaming is not very well understood. As sleep expert Ernest Hartmann points out in Scientific American, there’s a lot about sleep in general that we don’t know, including what sleep is for and why we experience REM (rapid eye movement). Dreaming is only another part of this mysterious puzzle, and is even more elusive, as it’s even harder to study than sleep is. Although there is no definitive word on the purpose, mechanics, and nature of dreams, scientists have been able to make inroads into the study of our nonwaking lives, theorizing why some dreams are different than others and why people experience dreams differently.
Are you having unusually realistic dreams? Here’s what science can tell you:
It’s all about REM.
Sleep is divided into five different stages: Stages 1, 2, 3,
4 and REM. REM sleep is characterized by a high
level of activity in the brain, as well as a temporary paralysis of the
muscles. During REM, our heart rate increases, our breathing speeds up, and our
eyes move back and forth beneath our lids. A small 2015 study found that our
eye movements actually mimic those of when we’re awake, only instead of
responding to images out in the world, they’re responding to dreams. The study
found that movements corresponded with new images appearing during sleeper’s
REM sleep is responsible for vivid dreams. We may dream during other sleep stages, but those dreams will feel fragmented; the types of dreams that have elaborate storylines and complex imagery are fueled by REM.
We sleep in cycles. We first experience REM 70 to 90 minutes after falling asleep, and we go through a number of sleep cycles throughout the night, with REM cycles increasing in length as the night goes on. People are best able to remember their dreams when awakened from REM (as opposed to naturally shifting to other parts of the sleep cycle). If you awake unnaturally (through an alarm, for example), and the dream you just had feels unusually vivid to you, it may be because you were still in a REM stage when you woke up.
There are a few factors that may affect the vividness of your dreams:
getting enough sleep can lead to more intense dreaming. A 2005 study found
that when subjects didn’t get enough REM sleep one night, their brains tried to
make up for it the next, by engaging in longer periods of REM. Sleep for
sleep-deprived people also tends to be more extreme; neurologist Mark Mahowald
of the University of Minnesota told Scientific
American, “When someone is sleep deprived we see greater
sleep intensity, meaning greater brain activity during sleep; dreaming is
definitely increased and likely more vivid.” Scientific American terms this effect “REM rebound,” and it can
occur in a variety of situations.
Low blood sugar
For people with diabetes, unusually strange, vivid, or nightmarish dreams are worth paying attention to. These intense dreams can be a symptom of nocturnal hypoglycemia, or low blood sugar, which can be extremely dangerous if untreated.
Alcohol and other substances.
Alcohol, nicotine, anti-depressants, and blood pressure
medication all suppress REM sleep. When people stop using these substances,
they can experience REM rebound and have unusually vivid, intense dreams.
Mental Health Issues
Vivid or disturbing dreams can be symptoms of serious mental health issues. Bipolar disorder, for example, can cause aberrations in a sleeper’s REM sleep, which in turn can affect dreaming. People suffering from post-traumatic stress disorder (PTSD) also experience heightened rates of nightmares and vivid flashbacks.
Pregnancy can do a number on your dreaming life. Patricia
Garfield, PhD, author of Creative Dreaming, explained to WebMD, “There
is a greater
amount of actual dreaming and dream recall when a woman is
pregnant than at any other time during her life.” She adds that dreams can say
a lot about the pregnancy itself, saying, “The dreams will relate to her
condition of pregnancy, the trimester she is in, and what is going on in her
body at the time.” Garfield suggests that dreaming during pregnancy is affected
by three main factors: First, fluctuations in hormones can affect how you dream. Second, pregnant
women simply sleep a lot, and more sleep means there are more dreams to
remember. Finally, pregnant women tend to get up more often in the night than
other people (because they need to pee, or the baby is moving), and when you
wake up frequently, you’re more likely to remember your dreams throughout the
night (as opposed to the one you have right before waking in the morning).